Supersonic compressors of the centrifugal or axial flow and centrifugal types



Dec. 5, 1967 J. PLOTKOWIAK 3,35

SUPERSONIC COMPRESSORS OF THE CENTRIFUGAL OR AXIAL FLOW AND CENTRIFUGAL TYPES Filed May 10, 1965 4 Sheets-Sheet 1 Dec. 5, 1967 J. PLOTKOWIAK 3,356,289

SUPERSONIC COMPRESSORS OF THE CENTRIFUGAL OR AXIAL FLOW AND CENTRIFUGAL TYPES Filed May 10, 1965 4 Sheets-Sheet 2 HHHI lHl 3,356,289 AXIAL Dec. 5, 1967 .1. PLOTKOWIAK v SUPERSONIC COMPRESSORS OF THE CENTRIFUGAL OR FLOW AND CENTRIFUGAL TYPES 4 Sheets-Sheet 3 Filed May 10, 1965 Dec. 5, 1967 J. PLOTKOWIAK 3,356,289

SUPERSONIC COMPRESSORS OF THE CENTRIFUGAL OR AXIAL FLOW AND CENTRIFUGAL TYPES Filed May 10, 1965 4 Sheets-Sheet 4.

United States Patent Ofi'lce 3,356,289 Patented Dec. 5, 1967 3 Claims. cl. 230-114 ABSTRACT F THE DISCLOSURE The compressor comprises, on the one hand, a rotor delivering at a supersonic absolute velocity a gaseous fluid to a set of dilfuser vanes, each of which comprises an upstream portion of adjustable angular setting and a fixed downward portion, and, on the other hand, a set of guide vanes of adjustable angular position, a common control device being provided for simultaneously adjusting the position of the upstream portions of the diffuser vanes and that of the guide vanes. This single control device is adapted to vary the flow rate of the compressor while ensuring an optimum operation thereof.

The present invention relates to supersonic compressors of the centrifugal type or of the axial flow and centrifugal type comprising a set of fixed guide vanes of adjustable angular setting, a bladed rotor disposed downstream of said set of guide vanes to receive a gaseous fluid therefrom, and a set of fixed diffuser vanes adapted to receive said gaseous fluid from said rotor at a supersonic absolute velocity.

The invention is more especially, but not exclusively, concerned with compressors of this kind having a single stage and of high compression ratio.

The chief object of the present invention is to provide a compressor of this kind which is better adapted to meet the requirements of practice than those known up to this time, in particular concerning the operation thereof for different values of the compressor flow rate.

The essential feature of the present invention consists, on the one hand, in making every vane of the supersonic diffuser in two portions, to wit an upstream portion of adjustable angular setting, the relative velocity of the gaseous fluid with respect to said upstream portion being, at least at some points thereof, higher than the local velocity of sound, and a downstream portion of fixed angular setting, the relative speed of the gaseous fluid with respect to said downstream portion being at all points lower than the local velocity of sound, and, on the other hand, in providing control means for adjusting, simultaneously and according to a predetermined law, both the angular setting of the upstream portions of the supersonic diffuser vanes and the angular setting of the guide vanes,

A preferred embodiment of the present invention will be hereinafter described with reference to the appended drawings, given merely by way of example, and in which:

FIG. 1 is a diagrammatic sectional view on the line I-I of FIG. 2, of a compressor made according to the present invention;

FIG. 2 is a longitudinal half section, with portions in elevation, illustrating an embodiment of the compressor of FIG. 1;

FIG. 3 is an explanatory diagram relative to the operation of the compressor of FIGS. 1 and 2;

FIG. 4 is a sectional view in a plane perpendicular to its axis of a portionof a supersonic set of vanes belonging to a compressor according to the present invention, said vanes being shown in a first position;

FIG. 5 is a view similar to FIG. 4 but showing the vanes in another position; and

FIG. 6 is a diagram illustrating the operation of a compressor acording to the present invention for different values of the flow rate.

The compressor according to the present invention comprises, as shown by FIGS. 1 and 2, a bladed rotor R delivering, at a supersonic absolute velocity, a gaseous fluid to a fixed supersonic diffuser D constituted by vanes 1 forming between them passages P.

The compressor further comprises, upstream of rotor R, a fixed set C of pivotally adjustable guide vanes 6 the angular setting of which is a Every vane 1 of dilfuser D comprises two portions, to wit an upstream portion 1a set at an angle an adjustable by pivoting about an axis XX, the relative speed of the gaseous stream with respect to said upstream portion 1a being, at least at some points, higher than the local velocity of sound, and a downstream portion b set at a fixed angle, the relative speed of the gaseous fluid with respect to said downstream portion 1b being at all points lower than the local velocity of sound.

There is provided a single control device 50 for adjusting, simultaneously and according to a predetermined law, the angular setting a of the upstream portions 1:: of diffuser vanes 1 and the angular setting a of guide vanes 6.

Advantageously, this predetermined law is adapted to ensure the best possible operation of the com ressor for different flow rates, i.e. a substantially shockless inflow of the fluid into rotor R and to a substantially shockless inflow of the fluid into supersonic diffuser D.

Such a law corresponds to the line L of FIG. 3 wherein:

The angular settings ca of the upstream portions 1a of the vanes of the supersonic diifuser D are plotted in abscissas, and

The angular settings et of guide panes 6 are plotted in ordinates.

On line L have been mounted the values of the flow rate coefficient g0, that is to say the values of the ratio of the actual flow rate of the compressor and of its nominal flow rate.

Control device 50 must act upon the setting a of the upstream portions 1a of vanes 1 and upon the setting w of vanes 6 in accordance with the law which links the values of ca and a In particular this control device 50 may be: either actuated manually, or actuated by a servo-mechanism, or again made to depend upon a parameter characterizing the operation of the compressor and of the plant with which said compressor cooperates.

FIG. 2 shows, by way of example, an embodiment of this control device, in this case of the mechanical type. Diffuser D comprises two support elements or flanges 2, the downstream portions 1b of the diffuser vanes forming interconnecting elements between said elements 2.

Every upstream vane portion 1a is mounted through a ggrew 3 and studs 4 on a journal 5 rotatable about axis Every pivot 5 is mechanically connected to control device 50.

Guide vanes 6 are mounted on their support C through pivots 7 also mechanically connected to control device 50.

For this purpose, the fixed frame 8 of the compressor carries an annular piece 9 of revolution about the axis of rotation of said compressor and which may be given angular displacements of small amplitude about the axis of said frame 8.

Annular piece 9 carries: on the one hand, a plurality of spindles 10 parallel to the axis of rotation of the compressor and corresponding each to one diffuser vane 1a 1b, each of said spindles being freely rotatable in the housing formed by a fork 11 carried by annular piece 9, and on the other hand, a plurality of spindles 12 extending radially with respect to the axis of rotation of the compressor, each spindle 12 corresponding to a guide vane 6 of set C, said spindles 12 being freely rotatable in respective housings 13 provided in annular piece 9.

Every pivot 5 of a vane portion 1a is connected to the corresponding spindle 11 through a link 14 one of the ends of which is fixed to pivot 5 and the other end of which is freely slidable in a bore 15 provided transversely in spindle 10.

Every pivot 7 of a guide vane 6 is connected to a corresponding spindle 12 through a link 16 one end of which is fixed to said pivot 7 and the other end of which is freely slidable in a bore 17 provided in said spindle 12 transversely thereto.

With such an arrangement any angular displacement of annular piece 9 under the action of a control mechanism will produce, on the one hand, a displacement of the ends of links 14 slidable in spindle 10, which displacement produces a pivoting of pivots 5 in the upstream portions 1a of the vanes 1 of supersonic diffuser D, and, on the other hand, a displacement of the ends of links 16 sliding in spindles 12, which displacement causes pivots 7, and therefore vanes 6, to pivot.

Rotation of annular piece 9 about its axis may be ensured as follows:

A rod 18 having a threaded portion 19 is rotatable about its axis through any suitable means, such for instance as manual means, not shown by the drawings.

A threaded nut 20 cooperating with the screw-threaded portion 19 of rod 18 is journalled at 21 in a fork 22 rigid with annular piece 9.

Such a control device permits of determining, with respect to each other, the respective values of angles it and a by a suitable choice, in particular, of the respective lengths of links 14 and 16.

It should be noted that, as shown by FIGS. 4 and 5, it is advantageous to give the upstream portion 1a of every diffuser vane a shape such that the passage Pa (upstream portion of passage P) defined by two contiguous portions It: has the shape of a supersonic diffuser whatever be the angle of setting a of said upstream portions 1a, the inlet cross section Sa constituting the throat of the diffuser. There is thus produced, at the level of a cross section Sc, the position of which depends, among other things, upon the flow rate in volume of the compressor and upon the angular setting of the movable upstream portions 1a of vanes 1, a straight shock wave of low intensity behind which the flow of the fluids has become subsonic.

As for the downstream portion 1b of every vane 1c, it is given a shape such that the passage Pb (downstream portion of passage P) between two contiguous downstream portions 1b is in the form of a subsonic diffuser the outlet cross section of which Sb is fixed.

It should be understood, that, for an operation of the compressor at high rate of delivery (for instance at maximum rate), the setting a of the upstream portion 1a of every vane 1 must be as shown by FIG. 4. The inlet cross section Sa is maximum and a straight shock wave is formed at the level of cross section Sc. The two portions 1:: and 1b of every vane 1 are supported from each other by a slot F of small thickness the inlet of which is located at the level of a cross section where the relative speed of the gaseous fluid is preferably lower than 0.8 time the local velocity of sound. It should be noted that this slot F improves the fiow of fluid about vane 1, on the one hand by suction of the limit layer formed on the low pressure face E of said vane and, on the other hand, by a blowing action on the high pressure face I of this vane.

When the compressor works with a low flow rate (for instance its minimum flow rate) the setting (1 of the upstream portion 1a of the vanes must be that indicated by FIG. 5. The inlet cross section Sa is minimum and a shock wave is formed at the level of cross section Sc (which is nearer to inlet cross section Sa than in the case of operation with a high flow rate) and the two portions 1a and 1b of vane 1 are separated from each other by a slot F of relatively great thickness.

This slot F therefore constitutes passage P through which is shunted a portion of the flow of gaseous fluid toward the contiguous passage P The inlet of passage P is at the level of a cross section where the relative speed of the gaseous fluid is preferably smaller than 0.5 time the local velocity of sound.

This single stage compressor has a very high compression ratio K and it may work with variable flow rates while keeping, on the one hand, a high compression ratio K and, on the other hand, a favorable efficiency.

These advantages are illustrated by FIG. 6 which shows two curves to wit:

On the one hand, curve T which represents the ratio of compression K in ordinates on the left hand axis and the flow rate coefficient (p, in abscissas, and, on the other hand, curve T which shows the values of the ratio R of the efi rciencies at different flow rates to the maximum efficiency (plotted in ordinates on the right hand axis line) the flow rate coefficient being plotted in abscissas.

These curves are relative to a compressor with the ratio between the peripheral velocity at the outlet of the rotor to the velocity of sound in the conditions of admission averaging 1.7. It will be found that the flow rate may vary between values corresponding to a flow rate coefficient of 0.25 to a value corresponding to a flow rate coefficient of 1.5, the pressure ratio and the efficiency pressure having acceptable values respectively.

In a general manner, while the above description discloses what is deemed to be a practical and efficient embodirnent of the present invention, said invention is not limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the invention as comprehended within the scope of the appended claims.

What I claim is:

1. In a gaseous fluid supersonic compressor of the combined axial and centrifugal flow type, in combination, a fixed frame, means defining a central inlet, a set of first pivots radially disposed in said frame about an axis to which said pivots are transverse, a set of guide vanes adapted to receive a stream of gaseous fluid from said inlet, each of said guide vanes being carried by one of said pivots, said guide vanes having an angular setting adjustable by rotation of said pivots in said frame, a bladed rotor disposed downstream of said set of guide vanes to receive a stream of gaseous fluid therefrom, the axis of said rotor being the axis about which said first pivots are radially disposed, a diffuser adapted to receive the stream of gaseous fluid issuing from said rotor at a supersonic absolute velocity, said diffuser comprising two annular supports coaxial with said rotor, a plurality of second pivots parallel to the rotor axis in one of said supports, a plurality of vanes located between said two supports, each of said last mentioned vanes being made of two portions, a rotatable upstream portion and a fixed downstream portion, said downstream portion being rigidly fixed to said two supports in such manner as to brace said two supports together and said upstream portion being carried by one of said last mentioned pivots, said vanes defining means for causing the relative velocity of said gaseous fluid to remain supersonic from the leading edges of said upstream portions to intermediate points of passages between adjacent vanes and then to become subsonic from said points to the trailing edges of said downstream portions, and control means mechanically connected to each pivot carrying one of said guide vanes and to each pivot carrying one of said upstream portions of said diffuser vanes for simultaneously adjusting the an 'gular setting of said guide vanes and of the upstream portions of said diifuser vanes.

2. A supersonic compressor according to claim 1 wherein said control means comprise, an annular piece coaxial with the compressor, said annular piece being provided with a first set of housings, a first set of spindles parallel to the compressor axis, each of said spindles being pivotally located in one of said housings, each of said spindles being provided with a transverse bore, a first set of links, one of each of said links being fixed to one of said second pivots carrying said upstream portions of said diffuser vanes, the other end being slidable in the transverse bore of one of said spindles, said annular piece being provided with a second set of housings, a second set of spindles each pivotally located in one of said second housings, respectively, each of said second spindles being provided with a transverse bore, a second set of links, one end of each of said links of the second set being fixed to one of said pivots carrying said guide vanes, the other end being slidable in the transverse bore of one of said spindles of the second set, and means for pivoting said annular piece about the compressor axis in such manner as to change the angular setting of said guide vanes and of the upstream portions of said diffuser vanes.

3. A gaseous fluid supersonic compressor of the axial flow and combined axial and centrifugal flow types which comprises, in combination, means defining a central inlet and an outlet, a bladed rotor disposed to receive a stream of gaseous fluid from said inlet and to deliver it at supersonic absolute velocity, a set of diifuser vanes adapted to receive the stream of gaseous fluid issuing from said rotor, said vanes leaving between them passages for the flow of said gaseous fluid, each of said last mentioned vanes being made of two portions, an upstream portion capable of rotation and a fixed downstream portion, said rotation taking place about an axis parallel to the axis of said rotor, said vanes defining means for causing the relative velocity of said gaseous fluid to remain supersonic [from the leading edges of said upstream portions to intermediate points of said passages and then to become subsonic from said points to the trailing edges of said downstream portions, each of said upstream vane portions being spaced from its associated downstream vane portion as always to leave slots therebetween, said vanes each including a low pressure face and a high pressure face, the point at which each of said slots starts from the low pressure face of the corresponding vane being nearer to the leading edge of said vane than the point at which said slot ends in the high pressure face of said vane, the cross section of said slots increasing when the cross section of the leading portion of said passages between vanes is decreased by the pivoting of said adjustable vane portions and vice-versa, and control means for adjusting the angular setting of the upstream portions of said diffuser vanes about their respective axes in accordance with the operation of the compressor at different flow rates.

References Cited UNITED STATES PATENTS 1,771,711 7/1930 Hahn 230-114 2,654,410 7/1953 Banger et a1. 230--1l4 2,770,943 11/ 1956 Beale 230 -114 3,156,407 11/ 1964 Bourguard 230- 3,23 7,564 3 1966 Hartland 10397 FOREIGN PATENTS 1,096,536 1/ 1961 Germany.

HENRY F. RADUAZO, Primary Examiner. 

1. IN A GASEOUS FLUID SUPERSONIC COMPRESSOR OF THE COMBINED AXIAL AND CENTRIFUGAL FLOW TYPE, IN COMBINATION, A FIXED FRAME, MEANS DEFINING A CENTRAL INLET, A SET OF FIRST PIVOTS RADIALLY DISPOSED IN SAID FRAME ABOUT AN AXIS TO WHICH SAID PIVOTS ARE TRANSVERSE, A SET OF GUIDE VANES ADAPTED TO RECEIVE A STREAM OF GASEOUS FLUID FROM SAID INLET, EACH OF SAID GUIDE VANES BEING CARRIED BY ONE OF SAID PIVOTS, SAID GUIDE VANES HAVING AN ANGULAR SETTING ADJUSTABLE BY ROTATION OF SAID PIVOTS IN SAID FRAME, A BLADED ROTOR DISPOSED DOWNSTREAM OF SAID SET OF GUIDE VANES TO RECEIVE A STREAM OF GASEOUS FLUID THEREFROM, THE AXIS OF SAID ROTOR BEING THE AXIS ABOUT WHICH SAID FIRST PIVOTS ARE RADIALLY DISPOSED, A DIFFUSER ADAPTED TO RECEIVE THE STREAM OF GASEOUS FLUID ISSUING FROM SAID ROTOR AT A SUPERSONIC ABSOLUTE VELOCITY, SAID DIFFUSER COMPRISING TWO ANNULAR SUPPORTS COAXIAL WITH SAID ROTOR, A PLURALITY OF SECOND PIVOTS PARALLEL TO THE ROTOR AXIS IN ONE OF SAID SUPPORTS, A PLURALITY OF VANES LOCATED BETWEEN SAID TWO SUPPORTS, EACH OF SAID LAST MENTIONED VANES BEING MADE OF TWO PORTIONS, A ROTATABLE UPSTREAM PORTION AND A FIXED DOWNSTREAM PORTION, SAID DOWNSTREAM PORTION BEING RIGIDLY FIXED TO SAID TWO SUPPORTS IN SUCH MANNER AS TO BRACE SAID TWO SUPPORTS TOGETHER AND SAID UPSTREAM PORTION BEING CARRIED BY ONE OF SAID LAST MENTIONED PIVOTS, SAID VANES DEFINING MEANS FOR CAUSING THE RELATIVE VELOCITY OF SAID GASEOUS FLUID TO REMAIN SUPERSONIC FROM THE LEADING EDGES OF SAID UPSTREAM PORTIONS TO INTERMEDIATE POINTS OF PASSAGES BETWEEN ADJACENT VANES AND THEN TO BECOME SUBSONIC FROM SAID POINTS TO THE TRAILING EDGES OF SAID DOWNSTREAM PORTIONS, AND CONTROL MEANS MECHANICALLY CONNECTED TO EACH PIVOT CARRYING ONE OF SAID GUIDE VANES AND TO EACH PIVOT CARRYING THE ONE OF SAID UPSTREAM PORTIONS OF SAID DIFFUSER VANES FOR SIMULTANEOUSLY ADJUSTING THE ANGULAR SETTING OF SAID GUIDE VANES AND OF THE UPSTREAM PORTIONS OF SAID DIFFUSER VANES. 